HP FlexFabric 5800, FlexFabric 5820X IP Multicast Configuration Guide

HPE 5820X & 5800 Switch Series

IP Multicast Configuration Guide

Part number: 5998-7383R Software version: Release 1810 Document version: 6W100-20160129

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Contents

Multicast overview ··························································································· 1

Information transmission techniques ·········································································································· 1 Multicast features ······································································································································· 3 Common notations in multicast ·················································································································· 4

Multicast advantages and applications ······································································································ 4 Multicast models ················································································································································ 4 Multicast architecture ········································································································································· 5

Multicast addresses ··································································································································· 5

Multicast protocols ····································································································································· 9 Multicast packet forwarding mechanism ·········································································································· 11 Multicast support for VPNs ······························································································································ 11

Introduction to VPN instances ·················································································································· 11

Multicast application in VPNs ··················································································································· 12

Configuring IGMP snooping ·········································································· 13

IGMP snooping basic concepts ················································································································ 13

How IGMP snooping operates ················································································································· 15

IGMP snooping proxying ·························································································································· 16

Protocols and standards ·························································································································· 18 IGMP snooping configuration task list ·············································································································· 18 Configuring basic IGMP snooping functions ···································································································· 19

Configuration prerequisites ······················································································································ 19

Enabling IGMP snooping ························································································································· 19

Specifying the version of IGMP snooping ································································································ 20

Setting the maximum number of IGMP snooping forwarding entries ······················································· 20

Configuring static multicast MAC address entries ···················································································· 21 Configuring IGMP snooping port functions ······································································································ 21

Configuration prerequisites ······················································································································ 21

Setting aging timers for dynamic ports ····································································································· 22

Configuring static ports ···························································································································· 22

Configuring a port as a simulated member host ······················································································ 23

Enabling IGMP snooping fast-leave processing ······················································································ 24

Disabling a port from becoming a dynamic router port ············································································ 24 Configuring an IGMP snooping querier ············································································································ 25

Configuration prerequisites ······················································································································ 25

Enabling IGMP snooping querier ············································································································· 25

Configuring parameters for IGMP queries and responses ······································································· 26

Configuring the source IP addresses for IGMP queries ··········································································· 27 Configuring IGMP snooping proxying ·············································································································· 27

Configuration prerequisites ······················································································································ 27

Enabling IGMP snooping proxying ··········································································································· 27

Configuring the source IP addresses for the IGMP messages sent by the proxy ···································· 28 Configuring IGMP snooping policies ················································································································ 28

Configuration prerequisites ······················································································································ 28

Configuring a multicast group filter ··········································································································· 28

Configuring multicast source port filtering ································································································ 29

Enabling dropping unknown multicast data ······························································································ 30

Enabling IGMP report suppression ·········································································································· 31

Setting the maximum number of multicast groups that a port can join ···················································· 31

Enabling multicast group replacement ····································································································· 32

Setting the 802.1p precedence for IGMP messages ··············································································· 33

Configuring a multicast user control policy ······························································································· 33

Enabling the IGMP snooping host tracking function ················································································ 34

Setting the DSCP value for IGMP messages ··························································································· 34 Displaying and maintaining IGMP snooping ···································································································· 35 IGMP snooping configuration examples ·········································································································· 35

Group policy and simulated joining configuration example (in a VLAN) ·················································· 36

Static port configuration example (in a VLAN) ························································································· 38

IGMP snooping querier configuration example ························································································ 41

IGMP snooping proxying configuration example ······················································································ 43

Multicast source and user control policy configuration example ······························································ 46 Troubleshooting IGMP snooping ····················································································································· 50

Layer 2 multicast forwarding cannot function ··························································································· 50

Configured multicast group policy fails to take effect ··············································································· 51 Appendix ·························································································································································· 51

Processing of multicast protocol messages ····························································································· 51

Configuring PIM snooping ············································································· 53

Overview ·························································································································································· 53 Configuring PIM snooping ································································································································ 54 Displaying and maintaining PIM snooping ······································································································· 54 PIM snooping configuration example (in a VLAN) ··························································································· 55 Troubleshooting PIM snooping ························································································································ 57

PIM snooping does not work ···················································································································· 57

Some downstream PIM-capable routers cannot receive multicast data ·················································· 58

Configuring multicast VLANs ········································································ 59

Sub-VLAN-based multicast VLAN ············································································································ 59

Port-based multicast VLAN ······················································································································ 60 Multicast VLAN configuration task list ·············································································································· 61 Configuring a sub-VLAN-based multicast VLAN ······························································································ 61

Configuration prerequisites ······················································································································ 61

Configuration guidelines ··························································································································· 61

Configuration procedure ··························································································································· 61 Configuring a port-based multicast VLAN ········································································································ 62

Configuration prerequisites ······················································································································ 62

Configuring user port attributes ················································································································ 62

Configuring multicast VLAN ports ············································································································ 63 Setting the maximum number of forwarding entries for multicast VLANs ························································ 64 Displaying and maintaining a multicast VLAN ································································································· 64 Multicast VLAN configuration examples ·········································································································· 64

Sub-VLAN-based multicast VLAN configuration example ······································································· 64

Port-based multicast VLAN configuration example ·················································································· 68

Configuring multicast routing and forwarding ················································ 72

Hardware compatibility ····································································································································· 72 Overview ·························································································································································· 72

RPF check mechanism ···························································································································· 72

Static multicast routes ······························································································································ 74

Multicast forwarding across unicast subnets ···························································································· 76

Multicast traceroute ·································································································································· 76 Configuration task list ······································································································································· 77 Enabling IP multicast routing ··························································································································· 78 Configuring multicast routing and forwarding ··································································································· 78

Configuration prerequisites ······················································································································ 78

Configuring static multicast routes ··········································································································· 79

Configuring a multicast routing policy ······································································································ 79

Configuring a multicast forwarding range ································································································· 80

Configuring the multicast forwarding table size ························································································ 80

Tracing a multicast path ··························································································································· 81

Enabling multicast optimization ················································································································ 81 Displaying and maintaining multicast routing and forwarding ·········································································· 82 Multicast routing and forwarding configuration examples ················································································ 83

RPF route change configuration example ································································································ 83

RPF route creation configuration example ······························································································· 85

Multicast forwarding over a GRE tunnel ··································································································· 87 Troubleshooting multicast routing and forwarding ··························································································· 91

Static multicast route failure ····················································································································· 91

Multicast data fails to reach receivers ······································································································ 91

Configuring IGMP ························································································· 92

IGMP versions ·········································································································································· 92

IGMPv1 overview ····································································································································· 92

IGMPv2 enhancements ···························································································································· 94

IGMPv3 enhancements ···························································································································· 94

IGMP SSM mapping ································································································································ 96

IGMP proxying ········································································································································· 97

IGMP support for VPNs ···························································································································· 97

Protocols and standards ·························································································································· 98 IGMP configuration task list ····························································································································· 98 Configuring basic IGMP functions ···················································································································· 98

Configuration prerequisites ······················································································································ 99

Enabling IGMP ········································································································································· 99

Specifying IGMP versions ······················································································································ 100

Configuring an interface as a static member interface ··········································································· 100

Configuring a multicast group filter ········································································································· 101

Setting the maximum number of multicast groups that an interface can join ········································· 101 Adjusting IGMP performance ························································································································· 101

Configuration prerequisites ···················································································································· 101

Configuring Router-Alert option handling methods ················································································ 102

Configuring IGMP query and response parameters ··············································································· 103

Enabling IGMP fast-leave processing ···································································································· 105

Enabling the IGMP host tracking function ······························································································ 105

Setting the DSCP value for IGMP messages ························································································· 106 Configuring IGMP SSM mapping ··················································································································· 106

Configuration prerequisites ···················································································································· 106

Enabling SSM mapping ·························································································································· 107

Configuring SSM mappings ··················································································································· 107 Configuring IGMP proxying ···························································································································· 107

Configuration prerequisites ···················································································································· 107

Enabling IGMP proxying ························································································································ 108

Configuring multicast forwarding on a downstream interface ································································ 108 Displaying and maintaining IGMP ·················································································································· 109 IGMP configuration examples ························································································································ 110

Basic IGMP functions configuration example ························································································· 110

SSM mapping configuration example ···································································································· 112

IGMP proxying configuration example ··································································································· 116 Troubleshooting IGMP ··································································································································· 117

No membership information exists on the receiver-side router ······························································ 117

Membership information is inconsistent on the routers on the same subnet ········································· 118

Configuring PIM ·························································································· 119

PIM-DM ·················································································································································· 119

PIM-SM ·················································································································································· 121

BIDIR-PIM ·············································································································································· 127

Administrative scoping ··························································································································· 130

PIM-SSM ················································································································································ 132

Relationship among PIM protocols ········································································································ 133

PIM support for VPNs ···························································································································· 134

Protocols and standards ························································································································ 134 Configuring PIM-DM ······································································································································ 134

PIM-DM configuration task list ··············································································································· 135

Configuration prerequisites ···················································································································· 135

Enabling PIM-DM ··································································································································· 135

Enabling state-refresh capability ············································································································ 136

Configuring state-refresh parameters ···································································································· 136

Configuring PIM-DM graft retry period ··································································································· 137

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Configuring PIM-SM ······································································································································· 137

PIM-SM configuration task list ················································································································ 137

Configuration prerequisites ···················································································································· 138

Enabling PIM-SM ··································································································································· 138

Configuring an RP ·································································································································· 139

Configuring a BSR ································································································································· 141

Configuring administrative scoping ········································································································ 144

Configuring multicast source registration ······························································································· 146

Disabling switchover to SPT ·················································································································· 147 Configuring BIDIR-PIM ·································································································································· 148

BIDIR-PIM configuration task list ··········································································································· 148

Configuration prerequisites ···················································································································· 148

Enabling PIM-SM ··································································································································· 149

Enabling BIDIR-PIM ······························································································································· 149

Configuring an RP ·································································································································· 150

Configuring a BSR ································································································································· 152

Configuring administrative scoping ········································································································ 155 Configuring PIM-SSM ···································································································································· 157

PIM-SSM configuration task list ············································································································· 157

Configuration prerequisites ···················································································································· 157

Enabling PIM-SM ··································································································································· 157

Configuring the SSM group range ·········································································································· 158 Configuring common PIM features ················································································································ 159

Configuration task list ····························································································································· 159

Configuration prerequisites ···················································································································· 159

Configuring a multicast data filter ··········································································································· 160

Configuring a hello message filter ·········································································································· 160

Configuring PIM hello options ················································································································ 161

Configuring the prune delay ··················································································································· 162

Configuring common PIM timers ············································································································ 163

Configuring join/prune message sizes ··································································································· 164

Configuring PIM to work with BFD ········································································································· 164

Setting the DSCP value for PIM messages ··························································································· 165 Displaying and maintaining PIM ····················································································································· 165 PIM configuration examples ··························································································································· 167

PIM-DM configuration example ·············································································································· 167

PIM-SM non-scoped zone configuration example ················································································· 170

PIM-SM admin-scope zone configuration example ················································································ 175

BIDIR-PIM configuration example ·········································································································· 181

PIM-SSM configuration example ············································································································ 186 Troubleshooting PIM ······································································································································ 188

A multicast distribution tree cannot be built correctly ············································································· 188

Multicast data abnormally terminated on an intermediate router ··························································· 189

RPs cannot join SPT in PIM-SM ············································································································ 190

RPT establishment failure or source registration failure in PIM-SM ······················································· 190

Configuring MSDP ······················································································ 192

How MSDP operates ······························································································································ 192

MSDP support for VPNs ························································································································ 197

Protocols and standards ························································································································ 197 MSDP configuration task list ·························································································································· 198 Configuring basic MSDP functions ················································································································ 198

Configuration prerequisites ···················································································································· 198

Enabling MSDP ······································································································································ 198

Creating an MSDP peer connection ······································································································· 199

Configuring a static RPF peer ················································································································ 199 Configuring an MSDP peer connection ·········································································································· 200

Configuration prerequisites ···················································································································· 200

Configuring MSDP peer description ······································································································· 200

Configuring an MSDP mesh group ········································································································ 200

Configuring MSDP peer connection control ··························································································· 201

Configuring SA message related parameters ································································································ 202

Configuration prerequisites ···················································································································· 202

Configuring SA message content ··········································································································· 202

Configuring SA request messages ········································································································· 203

Configuring SA message filtering rules ·································································································· 203

Configuring the SA cache mechanism ··································································································· 204 Displaying and maintaining MSDP ················································································································· 205 MSDP configuration examples ······················································································································· 205

PIM-SM Inter-domain multicast configuration ························································································ 205

Inter-AS multicast configuration by leveraging static RPF peers ··························································· 210

Anycast RP configuration ······················································································································· 214

SA message filtering configuration ········································································································· 218 Troubleshooting MSDP ·································································································································· 222

MSDP peers stay in down state ············································································································· 222

No SA entries exist in the router's SA cache ························································································· 222

Inter-RP communication faults in Anycast RP application ····································································· 222

Configuring MBGP ······················································································ 224

Overview ························································································································································ 224 Protocols and standards ································································································································ 224 MBGP configuration task list ·························································································································· 224 Configuring basic MBGP functions ················································································································ 225

Configuration prerequisites ···················································································································· 225

Configuration procedure ························································································································· 225 Controlling route advertisement and reception ······························································································ 225

Configuration prerequisites ···················································································································· 226

Configuring MBGP route redistribution ·································································································· 226

Configuring default route redistribution into MBGP ················································································ 226

Configuring MBGP route summarization ································································································ 227

Advertising a default route to an IPv4 MBGP peer or peer group ·························································· 227

Configuring outbound MBGP route filtering ··························································································· 228

Configuring inbound MBGP route filtering ······························································································ 229

Configuring MBGP route dampening ····································································································· 230 Configuring MBGP route attributes ················································································································ 230

Configuration prerequisites ···················································································································· 230

Configuring MBGP route preferences ···································································································· 230

Configuring the default local preference ································································································ 231

Configuring the MED attribute ················································································································ 231

Configuring the NEXT_HOP attribute ···································································································· 231

Configuring the AS_PATH attribute ······································································································· 232 Tuning and optimizing MBGP networks ········································································································· 233

Configuration prerequisites ···················································································································· 233

Configuring MBGP soft reset ················································································································· 233

Enabling the MBGP ORF capability ······································································································· 234

Configuring the maximum number of MBGP ECMP routes ··································································· 235 Configuring a large scale MBGP network ······································································································ 235

Configuration prerequisites ···················································································································· 235

Configuring IPv4 MBGP peer groups ····································································································· 235

Configuring MBGP community ··············································································································· 236

Configuring an MBGP route reflector ····································································································· 237 Displaying and maintaining MBGP ················································································································ 237

Displaying MBGP ··································································································································· 237

Resetting MBGP connections ················································································································ 238

Clearing MBGP information ··················································································································· 239 MBGP configuration example ························································································································ 239

Configuring multicast VPN (available only on the HPE 5800) ····················· 243

MD-VPN overview ·································································································································· 245

Multicast across VPNs ··························································································································· 247

M6VPE ··················································································································································· 249

Protocols and standards ························································································································ 250

How MD-VPN works ······································································································································ 250

Share-MDT establishment ····················································································································· 250

Share-MDT-based delivery ···················································································································· 253

MDT switchover ····································································································································· 257

Multi-AS MD VPN ··································································································································· 258 Multicast VPN configuration task list ·············································································································· 260 Configuring MD-VPN ····································································································································· 261

Configuration prerequisites ···················································································································· 261

Enabling IP multicast routing in a VPN instance ···················································································· 261

Configuring a share-group and an MTI binding ······················································································ 261

Configuring MDT switchover parameters ······························································································· 262

Configuring the RPF vector feature ········································································································ 263

Enabling data-group reuse logging ········································································································ 263 Configuring BGP MDT ··································································································································· 264

Configuration prerequisites ···················································································································· 264

Configuring BGP MDT peers or peer groups ························································································· 264

Configuring a BGP MDT route reflector ································································································· 264 Specifying the source IP address for multicast across VPNs ········································································ 265

Configuration prerequisites ···················································································································· 265

Configuration procedure ························································································································· 266 Displaying and maintaining multicast VPN ···································································································· 266 Multicast VPN configuration examples ·········································································································· 267

Single-AS MD VPN configuration ··········································································································· 267

Multi-AS MD VPN configuration ············································································································· 279

Multicast across VPNs configuration example (on the source-side PE) ················································ 292

Multicast across VPNs configuration example (on the receiver-side PE) ·············································· 294

M6VPE configuration example ··············································································································· 295 Troubleshooting MD-VPN configuration ········································································································ 302

A share-MDT cannot be established ······································································································ 302

An MVRF cannot be created ·················································································································· 302

Configuring MLD snooping ········································································· 304

Basic concepts in MLD snooping ··········································································································· 304

How MLD snooping operates ················································································································· 306

MLD snooping proxying ························································································································· 307

Protocols and standards ························································································································ 308 MLD snooping configuration task list ············································································································· 308 Configuring basic MLD snooping functions ···································································································· 309

Configuration prerequisites ···················································································································· 309

Enabling MLD snooping ························································································································· 309

Specifying the version of MLD snooping ································································································ 310

Setting the maximum number of MLD snooping forwarding entries ······················································ 310

Configuring IPv6 static multicast MAC address entries ········································································· 311 Configuring MLD snooping port functions ······································································································ 312

Configuration prerequisites ···················································································································· 312

Configuring aging timers for dynamic ports ···························································································· 312

Configuring static ports ·························································································································· 313

Configuring a port as a simulated member host ···················································································· 313

Enabling MLD snooping fast-leave processing ······················································································ 314

Disabling a port from becoming a dynamic router port ·········································································· 315 Configuring an MLD snooping querier ··········································································································· 315

Configuration prerequisites ···················································································································· 316

Enabling MLD snooping querier ············································································································· 316

Configuring parameters for MLD queries and responses ······································································ 316

Configuring the source IPv6 addresses for MLD queries ······································································· 317 Configuring MLD snooping proxying ·············································································································· 318

Configuration prerequisites ···················································································································· 318

Enabling MLD snooping proxying ·········································································································· 318

Configuring the source IPv6 addresses for the MLD messages sent by the proxy ································ 318 Configuring an MLD snooping policy ············································································································· 319

Configuration prerequisites ···················································································································· 319

Configuring an IPv6 multicast group filter ······························································································ 319

Configuring IPv6 multicast source port filtering ······················································································ 320

Enabling dropping unknown IPv6 multicast data ··················································································· 320

Enabling MLD report suppression ·········································································································· 321

Setting the maximum number of multicast groups that a port can join ·················································· 321

Enabling IPv6 multicast group replacement ··························································································· 322

Setting the 802.1p precedence for MLD messages ··············································································· 323

Configuring an IPv6 multicast user control policy ·················································································· 323

Enabling the MLD snooping host tracking function ················································································ 324

Setting the DSCP value for MLD messages ·························································································· 325 Displaying and maintaining MLD snooping ···································································································· 325 MLD snooping configuration examples ·········································································································· 326

IPv6 group policy and simulated joining configuration example (in a VLAN) ········································· 326

Static port configuration example (in a VLAN) ······················································································· 328

MLD snooping querier configuration example (in a VLAN) ···································································· 331

MLD snooping proxying configuration example (in a VLAN) ·································································· 333

IPv6 multicast source and user control policy configuration example (in a VLAN) ································ 336 Troubleshooting MLD snooping ····················································································································· 341

Layer 2 multicast forwarding cannot function ························································································· 341

Configured IPv6 multicast group policy fails to take effect ····································································· 341 Appendix ························································································································································ 342

Processing of IPv6 multicast protocol messages ··················································································· 342

Configuring IPv6 PIM snooping ·································································· 343

Overview ························································································································································ 343 Configuring IPv6 PIM snooping ····················································································································· 344 Displaying and maintaining IPv6 PIM snooping ····························································································· 344 IPv6 PIM snooping configuration example (in a VLAN) ················································································· 345 Troubleshooting IPv6 PIM snooping ·············································································································· 347

IPv6 PIM snooping does not work ·········································································································· 347

Some downstream IPv6 PIM-capable routers cannot receive multicast data ········································ 348

Configuring IPv6 multicast VLANs ······························································ 349

Configuration prerequisites ···················································································································· 351

Configuration guidelines ························································································································· 351

Configuration procedure ························································································································· 351 Configuring a port-based IPv6 multicast VLAN ······························································································ 352

Configuration prerequisites ···················································································································· 352

Configuring user port attributes ·············································································································· 352

Configuring IPv6 multicast VLAN ports ·································································································· 353 Setting the maximum number of forwarding entries for IPv6 multicast VLANs ·············································· 354 Displaying and maintaining an IPv6 multicast VLAN ····················································································· 354 IPv6 multicast VLAN configuration examples ································································································ 354

Sub-VLAN-based multicast VLAN configuration example ····································································· 354

Port-based multicast VLAN configuration example ················································································ 358

Configuring IPv6 multicast routing and forwarding ······································ 362

RPF check mechanism ·························································································································· 362

IPv6 multicast forwarding across IPv6 unicast subnets ········································································· 364 Configuration task list ····································································································································· 365 Enabling IPv6 multicast routing ······················································································································ 365 Configuring IPv6 multicast routing and forwarding ························································································ 366

Configuration prerequisites ···················································································································· 366

Configuring an IPv6 multicast routing policy ·························································································· 366

Configuring an IPv6 multicast forwarding range ···················································································· 367

Configuring the IPv6 multicast forwarding table size ············································································· 367 Displaying and maintaining IPv6 multicast routing and forwarding ································································ 368 IPv6 multicast routing and forwarding configuration example ········································································ 369

vii

Troubleshooting IPv6 multicast policy configuration ······················································································ 373

Abnormal termination of IPv6 multicast data ·························································································· 373

Configuring MLD ························································································· 374

MLD versions ········································································································································· 374

How MLDv1 operates ····························································································································· 374

How MLDv2 operates ····························································································································· 376

MLD message types ······························································································································ 377

MLD SSM mapping ································································································································ 379

MLD proxying ········································································································································· 380

MLD support for VPNs ··························································································································· 381

Protocols and standards ························································································································ 381 MLD configuration task list ····························································································································· 381 Configuring basic MLD functions ··················································································································· 382

Configuration prerequisites ···················································································································· 382

Enabling MLD ········································································································································· 382

Configuring the MLD version ·················································································································· 383

Configuring an interface as a static member interface ··········································································· 383

Configuring an IPv6 multicast group filter ······························································································ 384

Setting the maximum number of IPv6 multicast groups that an interface can join ································· 384 Adjusting MLD performance ·························································································································· 385

Configuration prerequisites ···················································································································· 385

Configuring Router-Alert option handling methods ················································································ 385

Configuring MLD query and response parameters ················································································ 386

Enabling MLD fast-leave processing ······································································································ 388

Enabling the MLD host tracking function ································································································ 389

Setting the DSCP value for MLD messages ·························································································· 389 Configuring MLD SSM mapping ···················································································································· 389

Configuration prerequisites ···················································································································· 390

Enabling MLD SSM mapping ················································································································· 390

Configuring MLD SSM mappings ··········································································································· 390 Configuring MLD proxying ····························································································································· 390

Enabling MLD proxying ·························································································································· 391

Configuring IPv6 multicast forwarding on a downstream interface ························································ 391 Displaying and maintaining MLD ··················································································································· 392 MLD configuration examples ························································································································· 393

Basic MLD functions configuration example ·························································································· 393

MLD SSM mapping configuration example ···························································································· 395

MLD proxying configuration example ····································································································· 398 Troubleshooting MLD ····································································································································· 400

No member information exists on the receiver-side router ···································································· 400

Membership information is inconsistent on the routers on the same subnet ········································· 401

Configuring IPv6 PIM ·················································································· 402

IPv6 PIM-DM ·········································································································································· 402

IPv6 PIM-SM ·········································································································································· 405

IPv6 BIDIR-PIM ······································································································································ 410

IPv6 administrative scoping ··················································································································· 413

IPv6 PIM-SSM ········································································································································ 415

Relationship among IPv6 PIM protocols ································································································ 416

IPv6 PIM support for VPNs ···················································································································· 417

Protocols and standards ························································································································ 417 Configuring IPv6 PIM-DM ······························································································································ 417

IPv6 PIM-DM configuration task list ······································································································· 418

Configuration prerequisites ···················································································································· 418

Enabling IPv6 PIM-DM ··························································································································· 418

Enabling state-refresh capability ············································································································ 418

Configuring state refresh parameters ····································································································· 419

Configuring IPv6 PIM-DM graft retry period ··························································································· 419

viii

Configuring IPv6 PIM-SM ······························································································································ 420

IPv6 PIM-SM configuration task list ······································································································· 420

Configuration prerequisites ···················································································································· 421

Enabling IPv6 PIM-SM ··························································································································· 421

Configuring an RP ·································································································································· 422

Configuring a BSR ································································································································· 424

Configuring IPv6 administrative scoping ································································································ 427

Configuring IPv6 multicast source registration ······················································································· 428

Disabling switchover to SPT ·················································································································· 429 Configuring IPv6 BIDIR-PIM ·························································································································· 430

IPv6 BIDIR-PIM configuration task list ··································································································· 430

Configuration prerequisites ···················································································································· 430

Enabling IPv6 PIM-SM ··························································································································· 431

Enabling IPv6 BIDIR-PIM ······················································································································· 431

Configuring an RP ·································································································································· 431

Configuring a BSR ································································································································· 433

Configuring IPv6 administrative scoping ································································································ 436 Configuring IPv6 PIM-SSM ···························································································································· 438

IPv6 PIM-SSM configuration task list ····································································································· 438

Configuration prerequisites ···················································································································· 438

Enabling IPv6 PIM-SM ··························································································································· 438

Configuring the IPv6 SSM group range ································································································· 439 Configuring common IPv6 PIM features ········································································································ 440

Configuration task list ····························································································································· 440

Configuration prerequisites ···················································································································· 440

Configuring an IPv6 multicast data filter ································································································· 441

Configuring a hello message filter ·········································································································· 441

Configuring IPv6 PIM hello options ········································································································ 442

Configuring the prune delay timer ·········································································································· 443

Configuring common IPv6 PIM timers ···································································································· 443

Configuring join/prune message sizes ··································································································· 445

Configuring IPv6 PIM to work with BFD ································································································· 445

Setting the DSCP value for IPv6 PIM messages ··················································································· 446 Displaying and maintaining IPv6 PIM ············································································································ 446 IPv6 PIM configuration examples ·················································································································· 447

IPv6 PIM-DM configuration example ······································································································ 447

IPv6 PIM-SM non-scoped zone configuration example ········································································· 450

IPv6 PIM-SM admin-scope zone configuration example ······································································· 455

IPv6 BIDIR-PIM configuration example ·································································································· 468

IPv6 PIM-SSM configuration example ··································································································· 472 Troubleshooting IPv6 PIM ······························································································································ 475

A multicast distribution tree cannot be built correctly ············································································· 475

IPv6 multicast data is abnormally terminated on an intermediate router ··············································· 476

RPs cannot join the SPT in IPv6 PIM-SM ······························································································ 476

RPT cannot be established or a source cannot register in IPv6 PIM-SM ·············································· 477

Configuring IPv6 MBGP ·············································································· 478

Configuration prerequisites ···················································································································· 479

Configuring an IPv6 MBGP peer ············································································································ 479

Configuring a preferred value for routes from a peer or a peer group ··················································· 479 Controlling route distribution and reception ··································································································· 480

Configuration prerequisites ···················································································································· 480

Injecting a local IPv6 MBGP route ········································································································· 480

Configuring IPv6 MBGP route redistribution ·························································································· 480

Configuring IPv6 MBGP route summarization ······················································································· 481

Advertising a default route to a peer or peer group ················································································ 481

Configuring outbound IPv6 MBGP route filtering ··················································································· 481

Configuring inbound IPv6 MBGP route filtering ····················································································· 482

Configuring IPv6 MBGP route dampening ····························································································· 483

Configuring IPv6 MBGP route attributes ········································································································ 483

Configuration prerequisites ···················································································································· 484

Configuring IPv6 MBGP route preferences ···························································································· 484

Configuring the default local preference ································································································ 484

Configuring the MED attribute ················································································································ 484

Configuring the NEXT_HOP attribute ···································································································· 485

Configuring the AS_PATH attribute ······································································································· 485 Tuning and optimizing IPv6 MBGP networks ································································································· 486

Configuration prerequisites ···················································································································· 486

Configuring IPv6 MBGP soft reset ········································································································· 486

Enabling the IPv6 MBGP ORF capability ······························································································· 487

Configuring the maximum number of ECMP routes ··············································································· 488 Configuring a large scale IPv6 MBGP network ······························································································ 488

Configuration prerequisites ···················································································································· 488

Configuring an IPv6 MBGP peer group ·································································································· 488

Configuring IPv6 MBGP community ······································································································· 489

Configuring an IPv6 MBGP route reflector ····························································································· 490 Displaying and maintaining IPv6 MBGP ········································································································ 490

Displaying IPv6 MBGP ··························································································································· 490

Resetting IPv6 MBGP connections ········································································································ 491

Clearing IPv6 MBGP information ··········································································································· 492 IPv6 MBGP configuration example ················································································································ 492

Document conventions and icons ······························································· 495

Conventions ··················································································································································· 495 Network topology icons ·································································································································· 496

Support and other resources ······································································ 497

Accessing Hewlett Packard Enterprise Support ···························································································· 497 Accessing updates ········································································································································· 497

Websites ················································································································································ 498

Customer self repair ······························································································································· 498

Remote support ······································································································································ 498

Documentation feedback ······················································································································· 498

Index ··········································································································· 499

Multicast overview

As a technique that coexists with unicast and broadcast, the multicast technique effectively addresses the issue of point-to-multipoint data transmission. By enabling high-efficiency point-to-multipoint data transmission over a network, multicast greatly saves network bandwidth and reduces network load.

Using multicast technology, a network operator can easily provide bandwidth-critical and time-critical information services. These services include live webcasting, Web TV, distance learning, telemedicine, Web radio, and real-time video conferencing.

Unless otherwise stated, the term "multicast" in this document refers to IP multicast.

Information transmission techniques

The information transmission techniques include unicast, broadcast, and multicast.

Unicast

In unicast transmission, the information source must send a separate copy of information to each host that needs the information.

Figure 1 Unicast transmission

Host A

Receiver

Host B

Source

Host C

Receiver

Host D

IP network

Packets for Host B

Packets for Host D

Packets for Host E

Receiver

Host E

In Figure 1, assume that Host B, Host D and Host E need the information. A separate transmission channel must be established from the information source to each of these hosts.

In unicast transmission, the traffic transmitted over the network is proportional to the number of hosts that need the information. If a large number of hosts need the information, the information source must send a separate copy of the same information to each of these hosts. Sending many copies can place a tremendous pressure on the information source and the network bandwidth.

Unicast is not suitable for batch transmission of information.

Broadcast

In broadcast transmission, the information source sends information to all hosts on the subnet, even if some hosts do not need the information.

Figure 2 Broadcast transmission

Multicast

In Figure 2, assume that only Host B, Host D, and Host E need the information. If the information is broadcast to the subnet, Host A and Host C also receive it. In addition to information security issues, broadcasting to hosts that do not need the information also causes traffic flooding on the same subnet.

Broadcast is disadvantageous in transmitting data to specific hosts. Moreover, broadcast transmission is a significant waste of network resources.

Unicast and broadcast techniques cannot provide point-to-multipoint data transmissions with the minimum network consumption.

Multicast transmission can solve this problem. When some hosts on the network need multicast information, the information sender, or multicast source, sends only one copy of the information. Multicast distribution trees are built through multicast routing protocols, and the packets are replicated only on nodes where the trees branch.

Figure 3 Multicast transmission

As shown in Figure 3, the multicast source sends only one copy of the information to a multicast group. Host B, Host D and Host E, which are receivers of the information, must join the multicast group. The routers on the network duplicate and forward the information based on the distribution of the group members. Finally, the information is correctly delivered to Host B, Host D, and Host E.

To summarize, multicast has the following advantages:

• Advantages over unicast—Multicast traffic is replicated and distributed until it flows to the

farthest-possible node from the source. The increase of receiver hosts will not remarkably increase the load of the source or the usage of network resources

• Advantages over broadcast—Multicast data is sent only to the receivers that need it. This

reasonably uses network bandwidth and enhances network security. In addition, multicast data is not confined to the same subnet.

Multicast features

Multicast transmission has the following features:

• A multicast group is a multicast receiver set identified by an IP multicast address. Hosts join a

multicast group to become members of the multicast group before they can receive the multicast data addressed to that multicast group. Typically, a multicast source does not need to join a multicast group.

• An information sender is called a "multicast source." A multicast source can send data to

multiple multicast groups at the same time. Multiple multicast sources can send data to the same multicast group at the same time.

• All hosts that have joined a multicast group become members of the multicast group. The group

memberships are dynamic. Hosts can join or leave multicast groups at any time. Multicast groups are not subject to geographic restrictions.

• Routers or Layer 3 switches that support Layer 3 multicast are called "multicast routers" or

"Layer 3 multicast devices." In addition to providing the multicast routing function, a multicast router can also manage multicast group memberships on stub subnets with attached group members. A multicast router itself can be a multicast group member.

For a better understanding of the multicast concept, you can compare multicast transmission to the transmission of TV programs as shown in Table 1.

Table 1 Comparing TV program transmission and multicast transmission

TV transmission Multicast transmission

A TV station transmits a TV program through a channel.

A user tunes the TV set to the channel. A receiver joins the multicast group.

The user starts to watch the TV program transmitted by the TV station through the channel.

The user turns off the TV set or tunes to another channel.

Common notations in multicast

The following notations are commonly used in multicast transmission:

• (*, G)—Rendezvous point tree (RPT), or a multicast packet that any multicast source sends to

multicast group G. Here, the asterisk represents any multicast source, and "G" represents a specific multicast group.

• (S, G)—Shortest path tree (SPT), or a multicast packet that multicast source S sends to

multicast group G. Here, "S" represents a specific multicast source, and "G" represents a specific multicast group.

For more information about the concepts RPT and SPT, see "Configuring PIM" and "Configuring

IPv6 PIM."

A multicast source sends multicast data to a multicast group.

The receiver starts to receive the multicast data that the source is sending to the multicast group.

The receiver leaves the multicast group or joins another group.

Multicast advantages and applications

Multicast advantages

Advantages of the multicast technique include the following:

• Enhanced efficiency—Reduces the processor load of information source servers and network

devices.

• Optimal performance—Reduces redundant traffic.

• Distributed application—Enables point-to-multipoint applications at the price of minimum

network resources.

Multicast applications

The scenarios in which the multicast technique can be effectively applied are:

• Multimedia and streaming applications, such as Web TV, Web radio, and real-time video/audio

conferencing

• Communication for training and cooperative operations, such as distance learning and

telemedicine

• Data warehouse and financial applications (stock quotes)

• Any other point-to-multipoint application for data distribution

Multicast models

Based on how the receivers treat the multicast sources, the multicast models include any-source multicast (ASM), source-filtered multicast (SFM), and source-specific multicast (SSM).

ASM model

In the ASM model, any sender can send information to a multicast group as a multicast source. Receivers can join a multicast group (identified by a group address) and obtain multicast information addressed to that multicast group. In this model, receivers do not know the positions of the multicast sources in advance. However, they can join or leave the multicast group at any time.

SFM model

The SFM model is derived from the ASM model. To a sender, the two models appear to have the same multicast membership architecture.

The SFM model functionally extends the ASM model. The upper-layer software examines the source address of received multicast packets and permits or denies multicast traffic from specific sources. Therefore, receivers can receive the multicast data from only part of the multicast sources. To a receiver, not all multicast sources are valid because they are filtered.

SSM model

Users might be interested in the multicast data from only certain multicast sources. The SSM model provides a transmission service that enables users to specify the multicast sources that they are interested in at the client side.

In the SSM model, receivers have already determined the locations of the multicast sources. This is the main difference between the SSM model and the ASM model. In addition, a different multicast address range than the ASM/SFM model is used in the SSM model. Dedicated multicast forwarding paths are established between receivers and the specified multicast sources.

Multicast architecture

IP multicast addresses the following issues:

• Where should the multicast source transmit information to? (Multicast addressing.)

• What receivers exist on the network? (Host registration.)

• Where is the multicast source that provides data to the receivers? (Multicast source discovery.)

• How should information be transmitted to the receivers? (Multicast routing.)

IP multicast is an end-to-end service. The multicast architecture involves the following parts:

• Addressing mechanism—A multicast source sends information to a group of receivers

through a multicast address.

• Host registration—Receiver hosts can join and leave multicast groups dynamically. This

mechanism is the basis for management of group memberships.

• Multicast routing—A multicast distribution tree (a forwarding path tree for multicast data on the

network) is constructed for delivering multicast data from a multicast source to receivers.

• Multicast applications—A software system that supports multicast applications, such as video

conferencing, must be installed on multicast sources and receiver hosts. The TCP/IP stack must support reception and transmission of multicast data.

Multicast addresses

Network-layer multicast addresses (multicast IP addresses) enables communication between multicast sources and multicast group members. In addition, a technique must be available to map multicast IP addresses to link-layer multicast MAC addresses.

IP multicast addresses

• IPv4 multicast addresses:

Internet Assigned Numbers Authority (IANA) assigned the Class D address space (224.0.0.0 to

239.255.255.255) for IPv4 multicast.

Table 2 Class D IP address blocks and description

Address block Description

Reserved permanent group addresses. The IP address 224.0.0.0 is reserved. Other IP addresses can be used by routing protocols and for topology searching, protocol maintenance, and so

224.0.0.0 to 224.0.0.255

224.0.1.0 to 238.255.255.255

239.0.0.0 to 239.255.255.255

NOTE:

on. Table 3 lists common permanent group addresses. A packet destined for an address in this block is not forwarded beyond the local subnet regardless of the Time to Live (TTL) value in the IP header.

Globally scoped group addresses. This block includes the following types of designated group addresses:

• 232.0.0.0/8—SSM group addresses.

• 233.0.0.0/8—Glop group addresses.

Administratively scoped multicast addresses. These addresses are considered locally unique rather than globally unique, and can be reused in domains administered by different organizations without causing conflicts. For more information, see RFC 2365.

"Glop" is a mechanism for assigning multicast addresses between different ASs. By filling an AS number into the middle two bytes of 233.0.0.0, you get 255 multicast addresses for that AS. For more information, see RFC 2770.

Table 3 Some reserved multicast addresses

Address Description

224.0.0.1 All systems on this subnet, including hosts and routers.

224.0.0.2 All multicast routers on this subnet.

224.0.0.3 Unassigned.

224.0.0.4 DVMRP routers.

224.0.0.5 OSPF routers.

224.0.0.6 OSPF designated routers and backup designated routers.

224.0.0.7 Shared Tree (ST) routers.

224.0.0.8 ST hosts.

224.0.0.9 RIPv2 routers.

224.0.0.11 Mobile agents.

224.0.0.12 DHCP server/relay agent.

224.0.0.13 All Protocol Independent Multicast (PIM) routers.

224.0.0.14 RSVP encapsulation.

224.0.0.15 CBT routers.

224.0.0.16 Designated SBM.

224.0.0.17 All SBMs.

224.0.0.18 Virtual Router Redundancy Protocol (VRRP).

• IPv6 multicast addresses: Figure 4 IPv6 multicast format

The following describes the fields of an IPv6 multicast address as shown in Figure 4:

{ 0xFF—The most significant eight bits are 11111111, which indicates that this address is an

IPv6 multicast address.

{ Flags—The Flags field contains four bits as shown in Figure 5 and described in Table 4.

Figure 5 Flags field format

Table 4 Flags field description

Bit Description

0 Reserved, set to 0.

• When set to 0, it indicates that this address is an IPv6 multicast address without an embedded RP address.

• When set to 1, it indicates that this address is an IPv6 multicast address with an embedded RP address. (The P and T bits must also be set to 1.)

• When set to 0, it indicates that this address is an IPv6 multicast address not based on a unicast prefix.

• When set to 1, it indicates that this address is an IPv6 multicast address based on a unicast prefix. (The T bit must also be set to 1.)

• When set to 0, it indicates that this address is an IPv6

multicast address permanently-assigned by IANA.

• When set to 1, it indicates that this address is a transient, or dynamically assigned IPv6 multicast address.

{ Scope—The Scope field contains four bits, which indicate the scope of the IPv6

internetwork for which the multicast traffic is intended. Table 5 d

escribes the values of the

Scope field.

Table 5 Values of the Scope field

Value Meaning

0, F Reserved.

1 Interface-local scope.

2 Link-local scope.

3 Subnet-local scope.

4 Admin-local scope.

5 Site-local scope.

Value Meaning

6, 7, 9 through D Unassigned.

8 Organization-local scope.

E Global scope.

{ Group ID—The Group ID field contains 112 bits. It uniquely identifies an IPv6 multicast

group in the scope that the Scope field defines.

Ethernet multicast MAC addresses

A multicast MAC address identifies a group of receivers at the data link layer.

• IPv4 multicast MAC addresses:

As defined by IANA, the most significant 24 bits of an IPv4 multicast MAC address are 0x01005E. Bit 25 is 0, and the other 23 bits are the least significant 23 bits of a multicast IPv4 address.

Figure 6 IPv4-to-MAC address mapping

As shown in Figure 6, the most significant four bits of a multicast IPv4 address are 1110, which indicates that this address is a multicast address. Only 23 bits of the remaining 28 bits are mapped to a MAC address, so five bits of the multicast IPv4 address are lost. As a result, 32 multicast IPv4 addresses map to the same IPv4 multicast MAC address. Therefore, in Layer 2 multicast forwarding, a switch might receive some multicast data destined for other IPv4 multicast groups. The upper layer must filter such redundant data.

• IPv6 multicast MAC addresses:

As shown in Figure 7, the

most significant 16 bits of an IPv6 multicast MAC address are 0x3333.

The least significant 32 bits are the least significant 32 bits of a multicast IPv6 address.

Figure 7 An example of IPv6-to-MAC address mapping

Multicast protocols

Multicast protocols include the following categories:

• Layer 3 and Layer 2 multicast protocols:

{ Layer 3 multicast refers to IP multicast operating at the network layer.

Layer 3 multicast protocols—IGMP, MLD, PIM, IPv6 PIM, MSDP, MBGP, and IPv6

MBGP.

{ Layer 2 multicast refers to IP multicast operating at the data link layer.

Layer 2 multicast protocols—IGMP snooping, MLD snooping, PIM snooping, IPv6 PIM

snooping, multicast VLAN, and IPv6 multicast VLAN.

• IPv4 and IPv6 multicast protocols:

{ For IPv4 networks—IGMP snooping, PIM snooping, multicast VLAN, IGMP, PIM, MSDP,

and MBGP.

{ For IPv6 networks—MLD snooping, IPv6 PIM snooping, IPv6 multicast VLAN, MLD, IPv6

PIM, and IPv6 MBGP.

This section provides only general descriptions about applications and functions of the Layer 2 and Layer 3 multicast protocols in a network. For more information about these protocols, see the related chapters.

Layer 3 multicast protocols

Layer 3 multicast protocols include multicast group management protocols and multicast routing protocols.

Figure 8 Positions of Layer 3 multicast protocols

• Multicast group management protocols:

Typically, the Internet Group Management Protocol (IGMP) or Multicast Listener Discovery (MLD) protocol is used between hosts and Layer 3 multicast devices that directly connect to the hosts. These protocols define the mechanism of establishing and maintaining group memberships between hosts and Layer 3 multicast devices.

• Multicast routing protocols:

A multicast routing protocol runs on Layer 3 multicast devices to establish and maintain multicast routes and forward multicast packets correctly and efficiently. Multicast routes constitute loop-free data transmission paths from a data source to multiple receivers, that is, a multicast distribution tree.

In the ASM model, multicast routes include intra-domain routes and inter-domain routes.

{ An intra-domain multicast routing protocol discovers multicast sources and builds multicast

distribution trees within an AS to deliver multicast data to receivers. Among a variety of mature intra-domain multicast routing protocols, Protocol Independent Multicast (PIM) is most widely used. Based on the forwarding mechanism, PIM has dense mode (often referred to as "PIM-DM") and sparse mode (often referred to as "PIM-SM").

{ An inter-domain multicast routing protocol is used for delivery of multicast information

between two ASs. So far, mature solutions include Multicast Source Discovery Protocol (MSDP) and Multicast Border Gateway Protocol (MBGP). MSDP propagates multicast source information among different ASs. MBGP is an extension of the Multiprotocol Border Gateway Protocol (MP-BGP) for exchanging multicast routing information among different ASs.

For the SSM model, multicast routes are not divided into intra-domain routes and inter-domain routes. Because receivers know the position of the multicast source, channels established through PIM-SM are sufficient for the transport of multicast information.

Layer 2 multicast protocols

Layer 2 multicast protocols include IGMP snooping, MLD snooping, PIM snooping, IPv6 PIM snooping, multicast VLAN, and IPv6 multicast VLAN.

Figure 9 Positions of Layer 2 multicast protocols

• IGMP snooping and MLD snooping:

IGMP snooping and MLD snooping are multicast constraining mechanisms that run on Layer 2 devices. They manage and control multicast groups by monitoring and analyzing IGMP or MLD messages exchanged between the hosts and Layer 3 multicast devices. This effectively controls the flooding of multicast data in a Layer 2 network.

• PIM snooping and IPv6 PIM snooping:

PIM snooping and IPv6 PIM snooping run on Layer 2 devices. They determine which ports are interested in multicast data by analyzing the received IPv6 PIM messages. Then, they add the ports to a multicast forwarding entry. In this way, multicast data can be forwarded to only the ports that are interested in the data.

• Multicast VLAN and IPv6 multicast VLAN:

In the traditional multicast-on-demand mode, when users in different VLANs on a Layer 2 device need multicast information, the upstream Layer 3 device must forward a separate copy of the multicast data to each VLAN of the Layer 2 device. When the multicast VLAN or IPv6 multicast VLAN feature is enabled on the Layer 2 device, the Layer 3 multicast device sends

only one copy of multicast to the multicast VLAN or IPv6 multicast VLAN on the Layer 2 device. This approach avoids wasting network bandwidth and placing an extra burden on the Layer 3 device.

Multicast packet forwarding mechanism

In a multicast model, receiver hosts of a multicast group are usually located at different positions of the network. They are identified by the same multicast group address. To deliver multicast packets to these receivers, a multicast source encapsulates the multicast data in an IP packet with the multicast group address as the destination address. Multicast routers on the forwarding paths usually need to forward multicast packets that an incoming interface receives through multiple outgoing interfaces. Compared with a unicast model, a multicast model is more complex in the following aspects:

• To ensure multicast packet transmission in the network, different routing tables are used to

guide multicast forwarding. These routing tables include unicast routing tables and multicast routing tables (for example, the MBGP routing table) specially provided for multicast.

• To process the same multicast information from different peers received on different interfaces,

the multicast device performs a reverse path forwarding (RPF) check on each multicast packet. The result of the RPF check determines whether the packet is forwarded or discarded. The RPF check mechanism is the basis for most multicast routing protocols to implement multicast forwarding.

For more information about the RPF mechanism, see "Configuring multicast routing and forwarding"

and "Configuring IPv6 multicast routing and forwarding."

Multicast support for VPNs

Multicast support for VPNs refers to multicast applied in virtual private networks (VPNs).

Introduction to VPN instances

VPNs must be isolated from one another and from the public network. As shown in Figure 10, VPN A and VPN B separately access the public network through PE devices.

Figure 10 VPN networking diagram

VPN A

CE a2

CE b3

VPN BVPN B

CE a3

PE 3

VPN A

CE b1

CE a1

VPN A

CE b2

PE 1

PE 2

Public network

• The provider (P) device belongs to the public network. The customer edge (CE) devices belong

to their respective VPNs. Each CE device serves its own VPN and maintains only one set of forwarding mechanisms.

• The provider edge (PE) devices connect to the public network and the VPNs. Each PE device

must strictly distinguish the information for different networks, and maintain a separate forwarding mechanism for each network. On a PE device, a set of software and hardware that serve the same network forms an instance. Multiple instances can exist on the same PE device, and an instance can reside on different PE devices. On a PE device, the instance for the public network is called the public network instance, and those for VPNs are called VPN instances.

Multicast application in VPNs

A PE device that supports multicast for VPNs does the following operations:

• Maintains an independent set of multicast forwarding mechanisms for each VPN, including the

multicast protocols, PIM neighbor information, and multicast routing table. In a VPN, the device forwards multicast data based on the forwarding table or routing table for that VPN.

• Implements the isolation between different VPNs.

• Implements information exchange and data conversion between the public network and VPN

instances.

Multicast VPN implements multicast on MPLS L3VPN networks. As shown in Figure 10, when a multicast source in VPN A sends a multicast stream to a multicast group, only the receivers that belong to both the multicast group and VPN A can receive the multicast stream. The multicast data is multicast both in VPN A and on the public network.

Configuring IGMP snooping

This chapter describes IGMP snooping, how to configure IGMP snooping, configuration examples, troubleshooting methods, and an appendix about processing multicast protocol messages.

Overview

IGMP snooping is a multicast constraining mechanism that runs on Layer 2 devices to manage and control multicast groups.

By analyzing received IGMP messages, an IGMP snooping-enabled Layer 2 device establishes mappings between ports and multicast MAC addresses, and forwards multicast data based on these mappings.

As shown in Figure 11, without IGMP to all devices at Layer 2. With IGMP snooping enabled, the Layer 2 switch forwards multicast packets destined for known multicast groups are multicast to only the receivers that require the multicast data at Layer 2. This feature improves bandwidth efficiency, enhances multicast security, and helps per-host accounting for multicast users.

Figure 11 Before and after IGMP snooping is enabled on the Layer 2 device

snooping enabled, the Layer 2 switch floods multicast packets

IGMP snooping basic concepts

This section describes the basic concepts involved in IGMP snooping.

IGMP snooping related ports

As shown in Figure 12, Router A connects to the multicast source, IGMP snooping runs on Switch A and Switch B, and Host A and Host C are receiver hosts as members of a multicast group.

Figure 12 IGMP snooping related ports

The following describes the ports involved in IGMP snooping:

• Router port—Layer 3 multicast device-side port. Layer 3 multicast devices include designated

routers (DRs) and IGMP queriers. In Figure 12, Gig

abitEthernet 1/0/1 of Switch A and GigabitEthernet 1/0/1 of Switch B are router ports. The switch registers all its router ports in its router port list.

Do not confuse the "router port" in IGMP snooping with the "routed interface" commonly known as the "Layer 3 interface." The router port in IGMP snooping is the Layer 2 interface.

• Member port—Multicast receiver-side port. In Figure 12, GigabitEthern

et 1/0/2 and GigabitEthernet 1/0/3 of Switch A and GigabitEthernet 1/0/2 of Switch B are member ports. The switch registers all its member ports in its IGMP snooping forwarding table.

Unless otherwise specified, router ports and member ports in this document include both static and dynamic router ports and member ports.

NOTE:

An IGMP snooping-enabled switch deems that all its ports that receive IGMP general queries with the source IP address other than 0.0.0.0 or that receive PIM hello messages are dynamic router ports. For more information about PIM hello messages, see "Configuring PIM."

Aging timers for dynamic ports in IGMP snooping and related messages and actions

Timer Description

When a port receives an expected message, the

Dynamic router port aging timer

Dynamic member port aging timer

switch starts an aging timer for the port. When the timer expires, the dynamic router port ages out.

When a port dynamically joins a multicast group, the switch starts an aging timer for the port. When the timer expires, the dynamic member

Expected message before expiration

IGMP general query of which the source address is not 0.0.0.0 or PIM hello.

IGMP membership report.

Action after expiration

The switch removes this port from its router port list.

The switch removes this port from the IGMP snooping forwarding table.

Timer Description

port ages out.

NOTE:

In IGMP snooping, only dynamic ports age out. Static ports never age out.

How IGMP snooping operates

An IGMP snooping-enabled switch performs different actions when it receives different IGMP messages.

In this section, the involved ports are dynamic ports. For information about how to configure and remove static ports, see "Configuring static ports."

When receiving a general query

To check for the existence of multicast group members, the IGMP querier periodically sends IGMP general queries to all hosts and routers on the local subnet. All these hosts and routers are indentified by the multicast address 224.0.0.1.

After receiving an IGMP general query, the switch forwards it to all ports in the VLAN, except the port that received the query. The switch also performs one of the following actions:

• If the receiving port is a dynamic router port in the router port list, restarts the aging timer for the

port.

• If the receiving port is not in the router port list, adds it into the router port list as a dynamic

router port. It also starts an aging timer for the port.

Expected message before expiration

Action after expiration

When receiving a membership report

A host sends an IGMP report to the IGMP querier for the following purposes:

• If the host has been a member of a multicast group, responds to the query with an IGMP report.

• Applies for joining a multicast group.

After receiving an IGMP report, the switch forwards it through all router ports in the VLAN. it also resolves the address of the reported multicast group, and looks up the multicast forwarding table for a matching entry:

• If no match is found, the Layer 2 device creates a forwarding entry for the group with the

receiving port as an outing interface. It also marks the receiving port as a dynamic member port and starts an aging timer for the port.

• If a match is found but the receiving port is not in the forwarding entry, the Layer 2 device adds

the port as an outgoing interface to the entry. It also marks the port as a dynamic member port and starts an aging timer for the port.

• If a match is found and the receiving port is in the forwarding entry, the Layer 2 device restarts

the aging timer for the port.

A switch does not forward an IGMP report through a non-router port because of IGMP report suppression mechanism. Assuming the switch forwards a report message through a member port, all attached member receivers will receive the report and suppress their own reports. This makes the switch unable to know whether the reported multicast group still has active members attached to that port. For more information about the IGMP report suppression mechanism, see "Configuring IGMP."

When receiving a leave message

An IGMPv1 host does not send any leave messages when it leaves a multicast group. Therefore, the Layer 2 device cannot immediately update the status of the port that connects to the receiver host. In this case, when the aging timer for the multicast group on the port expires, the Layer 2 device

removes the port from the associated forwarding entry. For a static member port, this mechanism does not take effect.

When an IGMPv2 or IGMPv3 host leaves a multicast group, the host sends an IGMP leave message to the multicast router.

When the switch receives an IGMP leave message on a dynamic member port, the switch first examines whether a forwarding entry matches the group address in the message:.

• If no match is found. the switch directly discards the IGMP leave message.

• If a match is found but the receiving port is not in the forwarding entry, the switch directly

discards the IGMP leave message.

• If a match is found and the receiving port is in the forwarding entry, the switch forwards the

leave message to all router ports in the VLAN. Without knowing whether any other attached hosts are still listening to that group, the switch does not immediately remove the port from the forwarding entry. Instead, it restarts the aging timer for the port.

After receiving the IGMP leave message, the IGMP querier resolves the multicast group address in the message. Then, it sends an IGMP group-specific query to the multicast group through the port that received the leave message.

After receiving the IGMP group-specific query, the switch forwards the query through all its router ports in the VLAN and all member ports of the multicast group. Then, the switch waits for the responding IGMP reports from the directly connected hosts to check for the existence of members for the multicast group. For the port that receives the leave message (assuming that it is a dynamic member port), the Layer 2 device also performs one of the following actions:

• If the port receives an IGMP report before the aging timer expires, the switch restarts the aging

timer for the port.

• If the port does not receive an IGMP report when the aging timer expires, the switch removes

the port from the forwarding entry for the multicast group.

IGMP snooping proxying

You can configure the IGMP snooping proxying function on an edge device to reduce the number of IGMP reports and leave messages sent to its upstream device. The device configured with IGMP snooping proxying is called an IGMP snooping proxy. It is a host from the perspective of its upstream device.

NOTE:

Even though an IGMP snooping proxy is a host from the perspective of its upstream device, the IGMP membership report suppression mechanism for hosts does not affect it. For more information about the IGMP report suppression mechanism for hosts, see "Configuring IGMP."

Figure 13 Network diagram

IP network

Proxy & Querier

Switch A

Host A

Receiver

Host B

IGMP Querier

Router A

Query from Router A

Report from Switch A

Query from Switch A

Report from Host

Host C

Receiver

As shown in Figure 13, Switch A works as an IGMP snooping proxy. As a host from the perspective of the querier Router A, Switch A represents its attached hosts to send membership reports and leave messages to Router A. Tab le 6 lists th

e IGMP messages and their processing on an IGMP snooping

proxy.

Table 6 IGMP message processing on an IGMP snooping proxy

IGMP message Actions

When receiving an IGMP general query, the proxy forwards it to all ports except the port

General query

that receive the query. In addition, the proxy generates a report according to the group membership that it maintains and sends the report out of all router ports.

Group-specific query

Report

Leave

In response to the IGMP group-specific query for a certain multicast group, the proxy sends the report to the group out of all router ports if the forwarding entry for the group still contains a member port.

After receiving a report for a multicast group, the proxy looks up the multicast forwarding table for a matching forwarding entry.

• If a match is found and the matching entry contains the receiving port as a dynamic member port, the proxy restarts the aging timer for the port.

• If a match is found but the matching entry does not contain the receiving port, the proxy adds the port to the forwarding entry. It also marks the port as a dynamic member port and starts an aging timer for the port.

• If no match is found, the proxy creates a forwarding entry for the multicast group with the receiving port as an outgoing interface. It also marks the port as a dynamic member port and starts an aging timer for the port.

In response to an IGMP leave message for a multicast group, the proxy sends a group-specific query out of the receiving port. After making sure that no member port is contained in the forwarding entry for the multicast group, the proxy sends a leave message to the group out of all router ports.

Protocols and standards

RFC 4541, Considerations for Internet Group Management Protocol (IGMP) and Multicast Listener Discovery (MLD) Snooping Switches

IGMP snooping configuration task list

For the configuration tasks in this section, the following rules apply:

• The configurations made in IGMP-snooping view are effective for all VLANs. The configuration

made in VLAN view are effective for only the current VLAN. For a given VLAN, a configuration made in IGMP-snooping view is effective only if you do not make the same configuration in VLAN view.

• The configurations made in IGMP-snooping view are effective for all ports. The configurations

made in Layer 2 Ethernet interface view or Layer 2 aggregate interface view are effective for only the current port. The configurations made in port group view are effective for all ports in only the current port group. For a given port, a configuration made in IGMP-snooping view is effective only if you do not make the same configuration in Layer 2 Ethernet interface view, Layer 2 aggregate interface view, or port group view.

• The IGMP snooping configurations made on Layer 2 aggregate interfaces do not interfere with

the configurations made on member ports. In addition, the configurations made on Layer 2 aggregate interfaces do not take part in aggregation calculations. The configurations made on a member port of the aggregate group will take effect after the port leaves the aggregate group.

Task Remarks

uired.

Optional.

Configuring basic IGMP snooping functions

Configuring IGMP snooping port functions

Configuring an IGMP snooping querier

Configuring IGMP snooping proxying

Enabling IGMP snooping Req

Specifying the version of IGMP snooping Optional.

Setting the maximum number of IGMP snooping forwarding entries

Configuring static multicast MAC address entries Optional.

Setting aging timers for dynamic ports Optional.

Configuring static ports Optional.

Configuring a port as a simulated member host Optional.

Enabling IGMP snooping fast-leave processing Optional.

Disabling a port from becoming a dynamic router port Optional.

Enabling IGMP snooping querier Optional.

Configuring parameters for IGMP queries and responses

Configuring the source IP addresses for IGMP queries Optional.

Enabling IGMP snooping proxying Optional.

Configuring the source IP addresses for the IGMP messages sent by the proxy

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HP FlexFabric 5800, FlexFabric 5820X IP Multicast Configuration Guide

Specifications and Main Features

Frequently Asked Questions

User Manual

Multicast overview

Information transmission techniques

Unicast

Broadcast

Multicast

Multicast features

Common notations in multicast

Multicast advantages and applications

Multicast advantages

Multicast applications

Multicast models

ASM model

SFM model

SSM model

Multicast architecture

Multicast addresses

IP multicast addresses

Ethernet multicast MAC addresses

Multicast protocols

Layer 3 multicast protocols

Layer 2 multicast protocols

Multicast packet forwarding mechanism

Multicast support for VPNs

Introduction to VPN instances

Multicast application in VPNs

Configuring IGMP snooping

Overview

IGMP snooping basic concepts

IGMP snooping related ports

Aging timers for dynamic ports in IGMP snooping and related messages and actions

How IGMP snooping operates

When receiving a general query

When receiving a membership report

When receiving a leave message

IGMP snooping proxying

Protocols and standards

IGMP snooping configuration task list